G'day Bod,

"Is it possible to use PDF::API2 in taint mode ..."

I'd say the short answer is "yes".

Obviously, I can't reproduce your environment — apart from anything else, there's insufficient information, such as your Apache? configuration — however, the following test works fine.

ken@titan ~/tmp/www
$ perl -Mstrict -Mwarnings -Mautodie=:all -MCarp::Always -T -E '
    use FindBin qw{$RealBin};
    my $safepath;
    BEGIN {
        if ($RealBin =~ m!^(/home/.+?/(tmp|xyz)/www)!) {
            $safepath = "$1/../lib";
        }
        else {
            die "Insecure access!";
        }
    }
    use lib "$safepath";
    use PDF::API2;
    my $pdf = PDF::API2->new("some.pdf");
    $pdf->save("some.pdf");
'
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Changing the last two (new() & save()) lines to:

    my $pdf = PDF::API2->open("some.pdf");
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also works without any problems. I checked:

ken@titan ~/tmp/www
$ file some.pdf
some.pdf: PDF document, version 1.4, 0 pages
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I'm running Perl v5.36.0 and PDF::API2 v2.043.

You've included completely unknown code with "use cPanelUserConfig;". Clearly, we're unable to test that. Try removing all of the code related to PDF::API2 and see if cPanelUserConfig is the cause of your taint issue. Your report suggests that you think PDF::API2 is the source of the problem, but you don't say why; you could be working from a false premise.

I'd move strict and warnings to the start of your code. Was there a reason for putting these in the middle of the script?

It's been 10-20 years since I last wrote any CGI code; my knowledge is certainly not current. I seem to recall that its documentation included troubleshooting tips involving running a CGI script from the command line. Perhaps look into that and see if it's any help.

Have a look at "FindBin: KNOWN ISSUES" and what it says about issues with mod_perl. I'm very much guessing with this — I don't even know if you're using mod_perl — but it may be worth a look.

Take a look through "perlsec - Perl security" for anything that might help. Perhaps the suggested:

delete @ENV{qw(IFS CDPATH ENV BASH_ENV)};   # Make %ENV safer
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If none of those suggestions help, you'll have to step through your code to find out where problems are occurring.